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J Thorac Cardiovasc Surg 2008;135:1320-1321
© 2008 The American Association for Thoracic Surgery
Invited Commentary |
Oppido and colleagues favor exposure through a conventional left atriotomy. I prefer the transseptal approach, and I have a very low threshold for extending my incision into the dome of the left atrium, thereby creating optimal exposure of the valve, especially in small patients. Intraoperative valve testing requires that the valve be undistorted while static testing is taking place.
Dr Oppido didn't mention in his presentation, but transesophageal echocardiography was used in about 87% of their cases. We rely heavily on the postrepair transesophageal echocardiography in determining whether our repair is adequate. In complex repairs, we recommend performing a preliminary transesophageal echocardiogram after recovery of the myocardium has occurred but not necessarily before full rewarming has been completed. In about 10% of patients, we may go back to bypass and make adjustments to the repair. This approach allows fine-tuning of the repair. We always place a left atrial pressure monitoring catheter before separation from bypass. The postrepair analysis must be performed under optimal loading conditions if we are to make inferences about the quality and durability of the repair.
Most of the early reoperations in Oppido and colleagues' series occurred in patients younger than 1 year. Only 87% of the patients underwent transesophageal echocardiography at the time of the first repair. In our experience, analysis of the repair in the operating room is very important in predicting short- and long-term outcomes. When a patient is too small for a transesophageal echocardiographic probe, we use epicardial echocardiography to analyze the repair. We assume that the quality of the repair will never be better than as seen on the immediate postrepair transesophageal echocardiogram. The predischarge transesophageal echocardiogram often shows a little worse regurgitation. We integrate our operative findings with those of the postrepair transesophageal echocardiogram, and on a few occasions we've been able to modify the repair to improve function.
We agree with Oppido and colleagues that a very eclectic approach must be taken to repair the unusual pathology encountered in patients born with congenital abnormalities of the mitral valve. Oppido and colleagues have demonstrated that most abnormal mitral valves can be salvaged. In the future, preoperative 3-dimensional echocardiography could be useful in planning repair strategies. We don't have that available at our institution.
The goal of this surgery, as clearly stated by Oppido and colleagues, is not cure but postponement of mitral valve replacement as long as possible. I have several questions.
First, Dr Oppido, did you use epicardial echocardiography in those patients for whom transesophageal echocardiography was not available?
Dr Oppido. Yes. We strongly believe, as you do, that transesophageal echocardiography is the criterion standard for intraoperative evaluation before repair, to inform an appropriate repair, and to check the immediate result of the repair. As for the patients who didn't undergo transesophageal echocardiography, they did undergo epicardial echocardiography.
Dr Lamberti. Was any valve revised in the operating room on the basis of the postrepair transesophageal or epicardial echocardiogram?
Dr Oppido. Yes, we revised the repair in approximately 10% of the patients on the basis of what we saw on the transesophageal echocardiogram.
Dr Lamberti. So actually, all the patients had some form of echocardiography in the operating room?
Dr Oppido. Yes.
Dr Lamberti. In reading the article, that wasn't clear, and I was wondering whether the early failures correlated with patients who did not have an echocardiogram before leaving the operating room.
Dr Oppido. All the patients underwent either transesophageal echocardiography (which was done in nearly all patients, 87%) or epicardial echocardiography.
Dr Lamberti. Thank you. It's an excellent article.
Dr Rodolfo Neirotti (Cambridge, Mass). I agree that annuloplasty techniques involving a ring can be a problem in the pediatric population. Although rigid and flexible rings meet the needs of adults, they do not allow room for growth of the native annulus when implanted in children. I think that biodegradable rings will address this problem. Atrioventricular valve repair with this new technology is feasible, with good early and midterm results.
Dr Oppido. In this series, we didn't have any experience with absorbable annuloplasty devices, but we anticipate that they may be helpful in selected cases.
Dr Alain F. Carpentier (Paris, France). Dr Oppido, I congratulate you. When comparing this surgery to what I did in the past, it's obviously a tremendous improvement. The mortality has been reduced significantly, and also you followed the guidelines. Obviously, there has been a lot of progress made. I do have two questions.
First, you mentioned the need to have a sort of annuloplasty allowing the growth of the annulus, which is true for babies and people younger than 10 years but not for people older than 10 years. So do you have a different strategy, depending on the age, and particularly regarding using remodeling annuloplasty whenever possible, when you don't expect the need for growth of the annulus? That's my first question; I have another brief question afterward.
Dr Oppido. We used several techniques for annuloplasty, and we strongly believe that every patient with mitral regurgitation and annular dilation requires annuloplasty. So in the smaller patients it should be feasible to use the sort of interrupted posterior annuloplasty with three-times–folded PTFE. After being positioned in the posterior annulus, this band is cut in one or more points to allow room for growth. Some other techniques, such as interrupted mattress suture to compress the posterior annulus, were also done in the smaller patients.
Dr Carpentier. No, my question is specifically, do you have another strategy for older patients who can accommodate remodeling annuloplasty, that is to say, a complete ring? I noticed that you have patients as old as 20 years, or at least beyond 15 years. Of course, it's a strategy more for an adult than for a young baby.
Dr Oppido. Yes, of course, in adult patients we implant an adult-sized commercially available complete ring. We did it in 9 patients in this series: posterior band in 5 patients and posterior complete annuloplasty with PTFE in 7 patients.
Dr Carpentier. For my second question, how often have you been using leaflet enlargement with pericardial patching?
Dr Oppido. Posterior leaflet was enlarged in 10 patients; anterior leaflet was enlarged in 4 patients.
Dr Carpentier. And you haven't seen any calcification of the patch?
Dr Oppido. None at all.
Dr Carpentier. Thank you.
Dr Carlos Troconis (Miami, Fla). In your article, you did note that the mitral valve was replaced in 4 cases, 1 early and 3 late. What type of prosthesis did you use, mechanical or bioprosthesis? What size and technique? What criteria did you chose?
Dr Oppido. The main goal of our policy, first of all, is to implant a prosthesis only in the intra-annular position, so we tend to avoid any different kind of implant, such as supra-annular and so on. So we implanted in this series, as a primary replacement, 19-mm mechanical prostheses. And in the follow-up, during the reoperations, we implanted two 21-mm mechanical prostheses and a homograft valve as the fourth replacement. And it is interesting that we could implant the two 21-mm prostheses in patients who were operated on early in life; the annulus at the beginning, at the first operation, was 11 or 12 mm. That was a good result, I think.
Pedro J. del Nido (Boston, Mass). I also congratulate you. This is a follow-up to your previous study on recurrent mitral regurgitation. Now you are presenting more longitudinal information, and the results seem to hold up over the years.
My question relates to an area in which we've become much more interested, congenital mitral stenosis, particularly in the infant. It's a very different disease than regurgitation. Most of the problem appears to be at the leaflet level. Images like the one that you showed, with apparent short chordae, are in fact deceptive. In fact, if you put a light behind those leaflets, you see that the chords are much, much longer; they're simply covered by a layer of what looks like endocardial tissue that actually mats those chords together, and you can strip this tissue off the chords. Van Praag demonstrated this more than 20 years ago.
My question relates to your management of mitral stenosis. It appears that your approach is primarily that of leaflet augmentation or leaflet replacement, with pericardium or whatever available tissue you have. Have you looked into leaflet thinning and removal of the endocardial layer of tissue that actually creates much of the stenosis? My concern with the replacement approach is that it still leaves a funnellike mitral valve, and attempts at commissurotomy are just going to lead to regurgitation. So might a different approach be more applicable?
Dr Oppido. Thank you for your question. Yes, of course, I showed just a few of the techniques we used. And especially in patients with mitral stenosis and papillary muscle–commissural fusion, we used several techniques, such as removing the excessive tissue between the chordae, chordal fenestration (and when the stenosis was at the papillary muscle level, papillary muscle fenestration), and when there was stenosis at the commissural level, commissurotomy. Of course, these were also integrated with the posterior leaflet enlargement.
Dr del Nido. Can you comment about the durability of that approach? In other words, how many of those patients required reoperation?
Dr Oppido. You're talking about what patients?
Dr del Nido. Patients with congenital mitral stenosis.
Dr Oppido. In this series, we had 11 patients with congenital mitral stenosis. All are alive. Only 1 patient has moderate dysfunction, and 1 patient has required replacement.
Dr Giovanni Stellin (Padua, Italy). I congratulate you on your results. A similar experience from our group was presented 3 days ago at the meeting of the World Society for Pediatric and Congenital Heart Surgery. We have managed to reconstruct the whole spectrum of the mitral valves disease.
You showed an image of a mitral valve malformation that you have defined as papillary muscle–commissural fusion (Image shown in Brizard,16 figure 124-3). According to Capentier's classification, what you have shown is not papillary muscle–commissural fusion; it appears to me more like the typical hammock valve or perhaps a mitral arcade, a malformation defined by two big papillary muscles and small chordae. I therefore ask, how do you define a hammock valve or a mitral arcade?
Dr Oppido. Of course, there is a wide, continuous spectrum among those dysplastic valves, especially in the stenotic group; however, what we define as hammock mitral valve is a mitral valve with an extremely dysplastic subvalvular apparatus in which it is not even possible to recognize papillary muscle in the tensor apparatus, or with some dysmorphic papillary muscle displaced toward the base of the heart, just behind the posterior leaflet, pulling both leaflets toward the posterior part of the heart. That's how we define hammock valve; what we showed is for us papillary muscle–commissural fusion, or short chordae syndrome.
Related Article
J. Thorac. Cardiovasc. Surg. 2008 135: 1313-1321.
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